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Dongmo A.B.,University of Douala | Nkeng-Efouet P.A.,University of Dschang | Devkota K.P.,Tribhuvan University | Wegener J.W.,TU Munich | And 3 more authors.
Phytomedicine | Year: 2014

Tetra-acetylajugasterone C (TAAC) was found to be one of the naturally occurring compounds of the Cameroonian medicinal plant Vitex cienkowskii which is responsible for a vasorelaxant activity of an extract of this plant. The evaluation of the underlying mechanisms for the relaxing effect of TAAC was determined using aortic rings of rats and mice. TAAC produced a concentration-dependent relaxation in rat artery rings pre-contracted with 1 μM noradrenaline (IC50: 8.40 μM) or 60 mM KCl (IC50: 36.30 μM). The nitric oxide synthase inhibitor l-NAME (100 μM) and the soluble guanylate cyclase inhibitor ODQ (10 μM) significantly attenuated the vasodilatory effect of TAAC. TAAC also exerted a relaxing effect in aorta of wild-type mice (cGKI+/+; IC50 = 13.04 μM) but a weaker effect in aorta of mice lacking cGMP-dependent protein kinase I (cGKI -/-; IC50 = 36.12 μM). The involvement of calcium channels was studied in rings pre-incubated in calcium-free buffer and primed with 1 μM noradrenaline prior to addition of calcium to elicit contraction. TAAC (100 μM) completely inhibited the resulting calcium-induced vasoconstriction. The same concentration of TAAC showed a stronger effect on the tonic than on the phasic component of noradrenaline-induced contraction. This study shows that TAAC, a newly detected constituent of Vitex cienkowskii contributes to the relaxing effect of an extract of the plant. The effect is partially mediated by the involvement of the NO/cGMP pathway of the smooth muscle but additionally inhibition of calcium influx into the cell may play a role. © 2014 Elsevier GmbH. Source

Beckert U.,Hannover Medical School | Grundmann M.,Institute of Pharmaceutical Biology | Wolter S.,Hannover Medical School | Schwede F.,BIOLOG Life Science Institute | And 4 more authors.
Biochemical and Biophysical Research Communications | Year: 2014

In addition to the well-known second messengers cAMP and cGMP, mammalian cells contain the cyclic pyrimidine nucleotides cCMP and cUMP. The Pseudomonas aeruginosa toxin ExoY massively increases cGMP and cUMP in cells, whereas the Bordetella pertussis toxin CyaA increases cAMP and, to a lesser extent, cCMP. To mimic and dissect toxin effects, we synthesized cNMP-acetoxymethylesters as prodrugs. cNMP-AMs rapidly and effectively released the corresponding cNMP in cells. The combination of cGMP-AM plus cUMP-AM mimicked cytotoxicity of ExoY. cUMP-AM and cGMP-AM differentially activated gene expression. Certain cCMP and cUMP effects were independent of the known cNMP effectors protein kinases A and G and guanine nucleotide exchange factor Epac. In conclusion, cNMP-AMs are useful tools to mimic and dissect bacterial nucleotidyl cyclase toxin effects. © 2014 Elsevier Inc. All rights reserved. Source

Balgobind B.V.,Erasmus University Rotterdam | Zwaan C.M.,Erasmus University Rotterdam | Reinhardt D.,Hannover Medical School | Arentsen-Peters T.J.C.M.,Erasmus University Rotterdam | And 12 more authors.
Leukemia | Year: 2010

Translocations involving the mixed lineage leukemia (MLL) gene, localized at 11q23, frequently occur in pediatric acute myeloid leukemia (AML). We recently reported differences in prognosis between the different translocation partners, suggesting differences in biological background. To unravel the latter, we used microarrays to generate gene expression profiles of 245 pediatric AML cases, including 53 MLL-rearranged cases. Thereby, we identified a specific gene expression signature for t(9;11)(p22;q23), and identified BRE (brain and reproductive organ expressed) to be discriminative for t(9;11)(p22;q23) (P<0.001) when compared with other MLL subtypes. Patients with high BRE expression showed a significantly better 3-year relapse-free survival (pRFS) (8013 vs 30±10%, P=0.02) within MLL-rearranged AML cases. Moreover, multivariate analysis identified high BRE expression as an independent favorable prognostic factor within pediatric AML for RFS (HR=0.2, P=0.04). No significant differences were identified for 3-year event-free survival or for 3-year overall survival. Forced expression of BRE did not result in altered cell proliferation, apoptosis or drug sensitivity, which could explain the favorable outcome. In conclusion, overexpression of the BRE gene is predominantly found in MLL-rearranged AML with t(9;11)(p22;q23). Although further investigation for the role of BRE in leukemogenesis and outcome is warranted, high BRE expression is an independent prognostic factor for pRFS in pediatric AML. © 2010 Macmillan Publishers Limited All rights reserved. Source

Balgobind B.V.,Erasmus University Rotterdam | van den Heuvel-Eibrink M.M.,Erasmus University Rotterdam | De Menezes R.X.,Erasmus University Rotterdam | De Menezes R.X.,Center for Human and Clinical Genetics | And 17 more authors.
Haematologica | Year: 2011

Background Pediatric acute myeloid leukemia is a heterogeneous disease characterized by non-random genetic aberrations related to outcome. The genetic subtype is currently detected by different diagnostic procedures which differ in success rate and/or specificity. Design and Methods We examined the potential of gene expression profiles to classify pediatric acute myeloid leukemia. Gene expression microarray data of 237 children with acute myeloid leukemia were collected and a double-loop cross validation approach was used to generate a subtype-predictive gene expression profile in the discovery cohort (n=157) which was then tested for its true predictive value in the independent validation cohort (n=80). The classifier consisted of 75 probe sets, representing the top 15 discriminating probe sets for MLL-rearranged, t(8;21)(q22;q22), inv(16)(p13q22), t(15;17)(q21;q22) and t(7;12)(q36;p13)-positive acute myeloid leukemia. Results These cytogenetic subtypes represent approximately 40% of cases of pediatric acute myeloid leukemia and were predicted with 92% and 99% accuracy in the discovery and independent validation cohort, respectively. However, for NPM1, CEBPA, MLL(-PTD), FLT3(-ITD), KIT, PTPN11 and N/K-RAS gene expression signatures had limited predictive value. This may be caused by a limited frequency of these mutations and by underlying cytogenetics. This latter is exemplified by the fact that different gene expression signatures were discovered for FLT3-ITD in patients with normal cytogenetics and in those with t(15;17)(q21;q22)-positive acute myeloid leukemia, which pointed to HOXB-upregulation being specific for FLT3-ITD+ cytogenetically normal acute myeloid leukemia. Conclusions In conclusion, gene expression profiling correctly predicted the most prevalent cytogenetic subtypes of pediatric acute myeloid leukemia with high accuracy. In clinical practice, this gene expression signature may replace multiple diagnostic tests for approximately 40% of pediatric acute myeloid leukemia cases whereas only for the remaining cases (predicted as 'acute myeloid leukemia-other') are additional tests indicated. Moreover, the discriminative genes reveal new insights into the biology of acute myeloid leukemia subtypes that warrants followup as potential targets for new therapies.© Ferrata Storti Foundation. Source

Lee S.-G.,Yonsei University | Park T.S.,Kyung Hee University | Won S.C.,Yonsei University | Song J.,Yonsei University | And 4 more authors.
Cancer Genetics and Cytogenetics | Year: 2010

Translocations involving mixed lineage leukemia (MLL) gene at 11q23 are associated with de novo acute leukemia as well as therapy-related acute leukemia. More than 100 different translocations involving MLL have been described in acute leukemia, with more than 60 translocation partner genes characterized on the molecular level. In addition to various simple translocations affecting MLL, there are also complex forms involving three or more chromosomes. Here, we describe a novel three-way translocation of t(2;19;11)(p12;p13.3;q23) in a patient with acute lymphoblastic leukemia (ALL). In this translocation, the distal 19p13.3 joins the proximal 11q23 on der(11), whereas the distal 11q23 is translocated to 2p12. Three-way translocations involving 11q23 are often difficult to detect with cytogenetic means alone. In the present case, however, the chromosomes involved in the three-way translocation were readily identifiable by GTG banding. The MLL-MLLT1 fusion products from the derivative chromosome 11 were detected by reverse transcriptase-polymerase chain reaction (RT-PCR), and two splicing variant forms were confirmed by cloning and sequencing. Furthermore, the novel third partner gene, NRXN1, was detected by systematic breakpoint analysis using long-distance inverse-PCR methods (LDI-PCR). The apparent three-way translocation thus identified is noteworthy because few studies have reported complex rearrangements involving 11q23 and 19p13.3 in acute leukemias. © 2010 Elsevier Inc. All rights reserved. Source

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